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Formulas/maths/Hyperbola/Hyperbola with Shifted Centre

Hyperbola with Shifted Centre

Centre at (h, k). Identified by completing the square. All elements of the standard hyperbola apply with origin shifted to (h, k).
Derivation

For a hyperbola with centre at (h,k)(h, k), substitute X=xhX = x-h, Y=ykY = y-k:

(xh)2a2(yk)2b2=1\frac{(x-h)^2}{a^2} - \frac{(y-k)^2}{b^2} = 1

Identifying from a general equation: Ax2Cy2+Dx+Ey+F=0Ax^2 - Cy^2 + Dx + Ey + F = 0 (with A,C>0A, C > 0, no xyxy term) represents a hyperbola. Complete the square:

A(xh)2C(yk)2=KA(x-h)^2 - C(y-k)^2 = K

Divide by KK. If K>0K > 0: transverse axis parallel to x-axis; if K<0K < 0: parallel to y-axis.

Elements in original coordinates for (xh)2/a2(yk)2/b2=1(x-h)^2/a^2 - (y-k)^2/b^2 = 1:

ElementValue
Centre(h,k)(h, k)
Vertices(h±a,k)(h \pm a, k)
Foci(h±c,k)(h \pm c, k)
Asymptotesyk=±ba(xh)y - k = \pm\frac{b}{a}(x-h)
Directricesx=h±a/ex = h \pm a/e